In the late 80's / early 90's, I ran a service that collected and transferred Usenet news and email betwwen BBS systems and the rest of the world (using UUCP). Eventually I got a live Internet feed to run it all more efficiently, and very regularly dealt with adventurous hackers continually breaking in to my server. I actually didn't hate that because none of it ever got destructive, and I thought it was wildly clever. The pre-web Internet was a whole different world compared to now.
Over time, keeping my hobby business together taught me a whole lot about what eventually became known as a firewall. I was continually building firewall features (which I referred to as a fortified gateway because firewalls didn't really exist yet) and creating test cases to find new vulnerabilities and guard against them first. It was heavily influenced by a sort of "audit" script that was making its rounds that identified poorly configured (vulnerable) services, except that I was scripting cases for vulnerabilities I was finding on my own server, and also by watching what the clever hackers were up to. I got to know a lot of them personally, funny enough.
It was actually a lot of fun. Otherwise I would have just given up and worked at McD's or whatever.
When BBS's started to get their own more efficient feeds and didn't need my silly slow service anymore - in the mid 90's - I was approached by a company that built firewalls (they finally became a thing!), and ended up working in infosec ever since.
My intention was to raise enough money from the side hobby to put out an instrumental metal album. No album yet, but I certainly made a career out of penetration testing that lasted decades. Now I'm winding down, doing more advisory work, leaving the grunt work to the whippersnappers.
So, if you're looking for a wicked lead axeman, ring me up. Eventually I might get that album happening.